power: Set XLP_OUT at power off

[crawfxrd]

Disable VDD3 once at power off instead of setting it every cycle in the LED update logic.

[crawfxrd]

Presumably this is the cause of #320 (comment).

Enabling XLP_OUT probably has to be moved from board_init() to power_on().

[XV-02]

Does this need to be tested in tandem with #320 (comment) ?

In isolation, I'm seeing the power light flash amber for ~3 seconds or less when I hold the power-button to shut the machine off. I can't trigger the power light to flash by short-stroking the power button.

All of these are resolutions of the issues I was seeing in #320 (comment) . I'd need to check other systems before approving however.

Is there any specific expected behaviour I should be looking for while I do that? (Its a very limited change, but I figure best to ask)

[crawfxrd]

Does this need to be tested in tandem with #320 (comment) ?

No, I split this out to determine if this is the cause the incorrect LED behavior.

In isolation, I'm seeing the power light flash amber for ~3 seconds or less when I hold the power-button to shut the machine off.

• Do you hold it after power off, or release it when it powers off?
• Does that happen on release firmware?

Sounds like something is being left on. Probably bad.

Is there any specific expected behaviour I should be looking for while I do that?

One test is:

• Power off unit
• Remove AC power
• Apply AC power
• Ensure power LED does not turn on or blink

I will look into this more next week.

[XV-02]

* Do you hold it after power off, or release it when it powers off?

* Does that happen on release firmware?

So, I hold the button until the system powered down, and immediately release the button. It blinks there-after.

It does not happen on the currently released firmware.

[XV-02]

One test is:

* Power off unit

* Remove AC power

* Apply AC power

* Ensure power LED does not turn on or blink

Doing this, I notice that, upon returning the AC power, the power light goes from off to solid amber, though this is also true on our current firmware release.

A quick table of status light behaviour is steady-state situations. The results are the same for both released firmware, and with this PR.

AC	Battery State	Power State	---->	Power Status Light	Battery Status Light
In	Full	On		Solid Green	Solid Green
In	Full	Suspend		Flashing Green	Solid Green
In	Full	Off		Solid Amber	Solid Green
In	Partial	On		Solid Green	Solid Amber
In	Partial	Suspend		Flashing Green	Solid Amber
In	Partial	Off		Solid Amber	Solid Amber
Out	N/A	On		Solid Green	Off
Out	N/A	Suspend		Flashing Green	Off
Out	N/A	Off		Off	Off

I would also note that the behaviour between released firmware and this PR also differs when powering a system off with shutdown now while on AC:

• Released: Power light transitions from solid green to solid amber. Battery light remains as it was (amber for charging, green for full)
• This PR: Power and Battery lights turn off and stay off until AC is unplugged and plugged back in.

[crawfxrd]

XLP_OUT controls VDD3, which is used for standby power. darp8 schematics show it's asserted at AC_IN. So it's not correct to set it after transitioning to S5. It has to be set when in S5 and AC is unplugged.